This invention relates to air purifiers, and specifically to automated air purifiers.
Air purifiers have grown in popularity in recent years. A growing concern for health and an increased recognition of the risks associated with unclear air are largely responsible for this trend. For example, airborne pollutants can cause or contribute to a number of respiratory problems, including respiratory infections, asthma, and allergies. Additionally, some airborne pollutants can cause undesirable odors. While air purifiers are available in a wide variety of designs, a conventional air purifier includes a blower that moves air through a filter element. The blower and filter element are typically contained in a unitary housing and are arranged with the blower either drawing or pushing air through the filter element. A number of different filter elements with different filtering characteristics are commercially available. For example, particulate filters are available to remove particulate matter from air. A conventional particulate filter includes a substance, such as fiberglass or electret-type media, that traps particulate matter as air is passed therethrough. Another example, odor filters are available to remove odors from the air. A conventional odor filter includes activated carbon, or activated charcoal, which removes pollutants from the air primarily by absorption.
Conventional air purifiers suffer from a number of problems. These systems are inherently noisy. The sound of air moving through the system and the noise generated by the blower motor are primary contributors to the noise level of the system. The noise level of the air passing through the purifier may be reduced by lowering the velocity at which it moves through the housing and filter. This can be done by increasing the size of the air flow path or by lowering the volume of air moved through the system. Increasing the air flow path requires larger housings and therefore increasing the overall size of the purifier.
To control the velocity of the air through the purifier they typically have a manual control for the user to select a desired speed for the fan motor. Generally, a high fan speed passes a larger volume of air through the unit so as to quickly and effectively remove airborne particles from the air. These high fan speeds however create an undesirable noise level. Because of these noise problems users often utilize the air purifier at a lower fan speed, especially when the user is attempting to sleep. These low fan speeds however do not maximize the purification capabilities of the unit. Many users however do not change the fan speed so that the purifier may be utilized at a maximum level of performance at times when the user is not present.
Air purifiers have been designed to include a timing mechanism to energize the fan motor for a select period of time, such as one, two or four hours, from the initial, manual actuation of the timing mechanism. These air purifiers however operate for only that select period of time commencing at the time the operator initiates the operation.
Air purifiers have also been designed to include an automatic control system which energizes or de-energizes the unit based on the sensed measured quality of air about the unit. These units however operate at a maximum fan speed at all times under certain conditions. As such, the unit may have a lifespan which is greatly decreased due to its overuse and the unit may operate at a high speed when such is not desired due to the noise factor.
Accordingly, it is seen that a need remains for an automatic air purifier which overcomes these problems associated with the prior art. It is to the provision of such therefore that the present invention is primarily directed.
In a preferred form of the invention an air purifier comprises, in combination, a housing having an air inlet and an air outlet, a filter mounted within the housing between the air inlet and the air outlet, fan means for drawing air into the housing through the air inlet, through the filter and out of the housing through the air outlet, motor means for driving the fan means at a plurality of discrete speeds, and programmable control means for automatically operating the motor means at different speeds during different daily periods of time.